A traditional maximum power point tracking (MPPT) algorithm sees a solar array as if it were a single solar module. MPPT can pull and push current on all strings and solar modules in a solar array in an equivalent fashion. As such, if solar modules in the solar array operate at different working points on the I-V curve, due to differences in installation, fabrication, or degradation over time, an MPPT algorithm may not be able to find the maximum power point (MPP) for the solar array.
U.S. Pat. No. 7,602,080, issued on Oct. 13, 2009 and entitled “Systems and Methods to Balance Solar Panels in a Multi-Panel System,” discloses a local management unit for a solar module. The local management unit has a controller for controlling the operation of the solar module and a link module unit to provide connectivity to a power bus for energy delivery and/or for data communications. The entire disclosure of U.S. Pat. No. 7,602,080 is incorporated herein by reference.
In some situations, in solar panels, a simple, economical solution is desirable to reduce both power consumption and component cost for the circuitry supplying a controller, etc., running in the solar panels. Further, it is desirable that such a solution offer high reliability and high efficiency.
Further, it is desirable, for safety and security, that modules may be added only to panels that are compatible with those modules, to avoid electrical problems and reduce potential fire danger, as well as to help protect in some cases against theft or misuse.